This invention relates to a thermal by-pass valve with integral pressure relief. The valve is arranged to change fluid flow direction at a specific fluid temperature and also to relieve excess fluid pressure.
The invention finds application to systems such as hydrostatic drives. Such systems could use this valve on return lines where the fluid flow is to be directed back to the reservoir when the temperature is below a given point and directed to the oil cooling system when the fluid temperature is above this point. The integral relief is to relieve any pressure that would be detrimental to the cooling system.
The inventive valve includes a body providing an inlet port and a pair of outlet ports which are generally arranged in the form of a T and with the outlet ports being aligned. Mounted in the flow passage connecting the outlet ports is a temperature sensitive valve element which closes one or the other of the outlet ports depending upon the temperature of the fluid flowing in the passage. Additionally there is a pressure sensitive valve element which, in the illustration given, serves as the valve seat for the temperature sensitive valve element and which is moved out of seating relationship when the pressure exceeds a predetermined value.
Other objects, advantages and details of the construction and operation of the inventive valve can be seen in the ensuing description.